Some conventional printer systems require printing media to be uniformly preheated prior to printing to provide an aesthetic and durable output. Typical heaters employ radiant or convective heat sources adjacent to the paper path and "upstream" of the print head. These existing heaters have several disadvantages. A lack of uniformity in heating can cause non uniform printer output, and media warping or cockle. Warping can further aggravate non uniformity by bringing some portions of the medium closer to the heat source than other portions.
Existing heaters are less thermally efficient than is desirable, requiring high power consumption to preheat a sheet to a given temperature, and generating excess heat that must be dissipated. The excess heat increases the environmental temperature of other components in the printer housing, thereby threatening component reliability and operating life. Excess heat can require additional time for the temperature to stabilize in the printer to obtain uniform print output. In addition, excess heat is unwelcome in an office environment, and may pose a safety hazard or require cool-down delays for internal servicing of a printer.
These problems are solved in the design of the present invention by providing a media preheater having at least one movable platelet cooperative with a fixed heater plate.